Here is a quote from Amin at the time:

Amin defended the expulsion by arguing that he was "giving Uganda back to ethnic Ugandans".

https://en.wikipedia.org/wiki/Expulsion_of_Asians_from_Uganda

https://madrascourier.com/insight/what-idi-amins-expulsion-of-ugandan-asians-informs-us-about-racism/

There are many articles about the expulsion, I have included two.

OK, but if he regretted expelling them as he's portrayed in the film, then he was probably wrong for doing so.

@CelluloidFan said:

OK, but if he regretted expelling them, as he is portrayed in the film, then he was probably wrong for doing so.

The film was mostly fiction. I personally really liked the film (I gave it 8/10) but after reading about the film after I had seen it, I realized that the accuracy was suspect. It's too bad that the relationship between Amin & Garrigan wasn't real.

https://en.wikipedia.org/wiki/The_Last_King_of_Scotland_(film)#Historical_accuracy

I knew about the film being based on a novel. All you gotta do is check out the film's page on this site and I think it gives credit to the novelist.

It doesn't necessarily mean that Idi Amin didn't eventually regret throwing thousands of human beings out of Uganda for not being black enough, nor earn international infamy for doing so.

@NeoLosman said:

It is worth noting, however, that the extremeness of white racism should never efface the possibility of the emergence of such a politics. For if we forget that black people are flawed human beings like everyone else is, we may leave open the door for said people to imitate or maybe even outdo their oppressors -- the idea of a morally perfect, benign race of black people being just as reductive as the fantasies of the colonizer.

Amin clearly absorbed the teachings of Elijah Muhammad far more deeply than he did those of Ibn Rushd or Rumi

I don't know anything about the last two people you mentioned. As for the second one: asking for trouble, are we?